1. Field of the Invention
The present invention relates to transgenic plants and their preparation.
2. Brief Description of the Related Art
Phosphofrucktokinase (PFK :EC 2.7.1.11) is widely regarded as a key regulatory enzyme controlling the entry of carbon into glycolysis. Glycolysis, especially in plant cells, serves to supply both respiratory carbon for energy production and intermediates for other metabolic pathways. The potato tuber contains four forms of PFK (Kruger et al, Arch. Biochem. Biophys. 267, 690–700) and pyrophosphate fructose-6-phosphate phosphotransferase (PFP:EC 2.7.1.90) which can catalyse the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. PFK is present in both the cytosol and the amyloplast while PFP is only known to occur in the cytosol.
It has previously been thought that PFK alone controls the total glycolytic flux. However, we have now found that this is not the case. We introduced additional PFK into potato plants by genetic manipulation. Our results indicate that a substantial increase in PFK activity did not substantially alter flux through glycolysis but changed the pool sizes of intermediates. The results indicate that regulation of glycolytic flux may be achieved not only at the entry of carbon into the pathway but also exit from it. This finding has general applicability.